1. Field of the Invention
The present invention relates to a display device for a vehicle for displaying a fuel amount supplied to an engine that drives the vehicle, as well as a vehicle speed and a rotation rate of the engine.
2. Description of the Related Art
In order to drive an engine to provide power for a vehicle, petroleum fuel such as gasoline and light oil is used. To enhance economical efficiency during an engine driving operation, it has been desired to reduce fuel consumption, that is, to enhance fuel efficiency.
Fuel efficiency depends on driver's driving behaviors, and his or her economical driving may result in a better fuel efficiency. In order to encourage a driver to perform an economical driving operation, it has been suggested to provide a driver with a display showing fuel consumption as well as a current fuel-injection rate, as disclosed in JP H03-56827 A.
However, JP H03-56827 A discloses a display of a fuel efficiency calculated based on past average values of vehicle speed and fuel consumption. It has been difficult to determine how a current driving operation such as an accelerator pedal stroking affects the fuel efficiency.
Since fuel-injection rate significantly varies depending on the vehicle speed, the fuel efficiency during a higher-speed driving at a greater fuel-injection rate may be equal to that during a lower-speed driving at a smaller fuel-injection rate. Thus, it is difficult to determine whether or not the current driving operation such as an accelerator pedal stroking is economically enough, simply by observing the current fuel-injection rate by sight.